In pressure transducers of the type wherein pressure acting on a diaphragm results in a force which is transmitted to a sensor beam, the diaphragm is connected to the sensor beam by a shaft which acts perpendicularly to the diaphragm and to the sensor beam. The diaphragm is protected against damage due to overpressure conditions by means of an O-ring which contacts the transducer body and seals a fluid filled cavity between the diaphragm and the sensor beam, the incompressible fluid preventing excessive movement of the diaphragm under high differential pressure conditions. As the pressure increases, the O-ring continues to compress until a mechanical stop integral with the connecting shaft contacts the transducer body to prevent overstressing the sensor beam.
In the prior art design the connecting shaft must be very accurately located relative to the diaphragm, and the O-ring and mechanical stop must be accurately positioned on the shaft. As a result of the extreme accuracy required, even the slightest misalignment can cause the O-ring to fail to seal properly, which can result in damage to the diaphragm. Under extreme conditions of misalignment the O-ring can become extruded between the mechanical stop and the transducer body resulting in seal failure and thus damage to the diaphragm and/or excessive bending and thus overstress the sensor beam and diaphragm assembly.
Because of the foregoing, it has now become desirable to develop an improved connection between the diaphragm and the sensor beam of a pressure transducer.